1. Field of the Invention
The present invention relates generally to image data processing machines, and more specifically to an image data processing machine for implementing image processing of input image data with different resolution values in consideration of the resolution and qualities of image outputs and for attaining improvements in image quality through minimal processing steps and at reduced costs.
2. Discussion of the Background
In increasingly versatile image data processing machines such as digital duplication apparatuses and other similar apparatuses, several improvements have been made on image qualities. For example, the improvements in image qualities have been carried out with respect to image data expanded into a bitmap through correcting jaggies (or jagged edges) on contour lines of the images.
Some of the correction processes have been disclosed previously so as to reduce to the utmost the amount of required data that are stored in advance in a memory, and to carry out in a reduced period of time by a microprocessor and other devices through process steps as simple as possible to discriminate pixels to be corrected and determine correction data on the pixels discriminated to be corrected.
The correction processes include the methods that are briefly summarized as follows.
Namely, Japanese Laid-Open Patent Applications No. 5-207282 and 2000-236446 disclose image data processing carried out by recognizing a line segment feature of a boundary between a black pixel region and a white pixel region in image data expanded into a bitmap, replacing characteristics of the thus recognized line segment feature for respective necessary pixels with plural-bit pattern code information, discriminating whether the pixels are required to be corrected utilizing at least a portion of the pattern code information, and making corrections to the pixels discriminated as required to be corrected according to the code information.
In addition, an image data processing machine configured to implement the above noted image data processing includes a window for extracting data of respective pixels in a predetermined region centering around an objective pixel among image data expanded into a bitmap; a pattern recognition means for generating pattern code information of plural bits for characterizing the line segment feature concerning the objective pixel after recognizing a line segment feature of a boundary between a black pixel region and a white pixel region in the image data based on the data extracted by the window; a discriminant means, utilizing at least a portion of the pattern code information, for discriminating whether the objective pixel is required to be corrected; and a correction data memory for retrieving and afterward outputting correction data stored in advance, according to the pattern code information generated by the pattern recognition means as an address, for pixels discriminated as required to be corrected by the discriminant means.
In addition, the pattern recognition means generates, as the code information for characterizing the line segment feature recognized based on the extracted data, code information including several codes such as a first code for indicating the objective pixel for the pattern recognition as either black or white, a second code for the direction of line segment inclination either upward or downward, a third code for the steepness of the inclination, and a fourth code for the position of the objective pixel with respect to the end pixel of the line segment continuous in the horizontal and vertical direction.
According to such an image data processing method and image data processing machine as described hereinabove, image data processing is carried out by recognizing a line segment feature of the boundary part (for example, a contour line of a character and others) between a black pixel region and a white pixel region in image data expanded into a bitmap, replacing with plural-bit pattern code information for respective necessary pixels, discriminating whether the pixels are required to be corrected utilizing at least a portion of the pattern code information, and making corrections to the pixels discriminated as required to be corrected according to the code information.
In this method, therefore, it becomes unnecessary to generate and store in advance, as a template, all necessary characteristic patterns required to be corrected; and the steps to discriminate pixels required to be corrected and determine correction data for pixels discriminated as required to be corrected are carried out with more ease in a reduced period of time.
In addition, although data smoothing according to different resolutions of input image data has been made previously using each different image correction data, the method of smoothing has required so far a considerable volume of memory for storing image correction data used in the image processing, and the memory volume required for data conversion tends to increase more as data with a lower resolution are converted to data with a higher resolution (Japanese Laid-Open Patent Application No. 9-107475).
In those previous methods, therefore, the improvements have been made on image qualities of image data expanded into a bitmap through correcting jaggies on contour lines of the images with the data to be stored being reduced to the utmost and in a reduced period of time. In addition, output images with high quality have been provided based on resolution information on input image by selecting a method of suitably processing the image data at least in the case of no account of different values of resolution.